How does X-ray detect PCB?

In modern industrial production, X-ray detection can be used in the assembly of PCB components to detect whether there are defects on solder joints, such as holes, too much solder, too little solder, solder balls, solder disconnection and solder bridging. Using X-ray detection can also detect whether the device is missing, and show the center offset of the device pin and pad caused by poor mounting after reflow soldering.

Because the density of PCB components is generally high, the solder joints of a large number of components are hidden, such as BGA flip chip. More and more manufacturers use X-ray detection technology. X-ray detection technology is easy to confirm the defects of solder balls (such as no solder joints) and the bridging phenomenon at the lower part of the equipment.

At present, the widely used X-ray detection technology mainly includes two categories: transmission X-ray image (two-dimensional) and cross-section X-ray image (three-dimensional). For the transmission X-ray image mode, the device X-ray uses a point light source to transmit, and directly penetrates the PCB assembly in the vertical angle (90 °). The X-ray detection device and camera are placed under the PCB to obtain a gray image and record the existing solder joint defects. The missing components can also be detected. It can automatically compare with the relevant gray images confirmed in the design specification database in advance, and report any differences found, so as to achieve the purpose of PCB component detection.

The cross-section x-ray device adopts a biased rotating x-ray beam, which irradiates the PCB at an acute angle. In this way, the formed cross-sectional image can be focused on the top and bottom of the PCB to be detected. Move the PCB through the X-ray beam focusing plane, and the specific position on the PCB is clearly focused, while all other parts are in a blurred state.

For X-ray detection equipment, there are three basic forms: manual, semi-automatic and full-automatic. Manual X-ray detection equipment can generally provide flexible and economical X-ray detection, which can be used in different stages of the manufacturing process. These include: component input, process monitoring, quality control and failure analysis. The operator visually analyzes the X-ray image to confirm what defects are displayed. The detection provided by such equipment is quite flexible and can speed up the execution time. It can be operated without expensive training or equipment programming.

Semi automatic X-ray detection equipment is equipped with mechanical observation and device position programmable console. The comprehensive analysis of device mounting and welding points is based on preset gray parameters. Generally, the program can be set by initially setting one PCB assembly board that has been confirmed to be of good quality, or using CAD (computer-aided design) to mount information and navigation program. Semi automatic X-ray testing equipment has considerable reliability, which can provide more check productivity than manual operation equipment.

Automatic X-ray detection equipment is usually used in applications requiring high output and low complexity. It is characterized by the use of transmission belt technology and is designed to operate at a linear speed. All detection work is in an automated state, and its operation basis is mainly based on the analysis of images.

With the increasing use of new components on PCB, the requirements for PCB testing are becoming higher and higher. Starting from a good performance price ratio, choosing effective and reasonable testing equipment is an effective means to ensure product quality and reduce costs for electronic product manufacturers, and it also provides unlimited business opportunities for testing equipment manufacturers.